feat(telemetry): implement storage layer (Phase 1) #20
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| # Session Handoff | ||
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| Persistent context bridge for autonomous ROADMAP execution across sessions. Each session reads this file at startup and updates it after completing a phase. | ||
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| --- | ||
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| ## Current State | ||
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| | Field | Value | | ||
| | ------------------------ | --------------------------- | | ||
| | **Active Wave** | Wave 1: Core Infrastructure | | ||
| | **Active Package** | telemetry | | ||
| | **Last Completed Phase** | telemetry phase 1 | | ||
| | **Last Session** | 2026-04-04 | | ||
| | **ROADMAP Status** | Phase 1 complete | | ||
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| --- | ||
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| ## Completed Work | ||
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| | Wave | Package | Phase | Title | | ||
| | ------ | --------- | ------- | ------------------------------- | | ||
| | Wave 1 | telemetry | Phase 0 | Foundation (types, scaffolding) | | ||
| | Wave 1 | telemetry | Phase 1 | Storage Layer (Memory + File) | | ||
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| --- | ||
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| ## Key Decisions (ADR Summary) | ||
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| - **Storage backends are pluggable**: `StorageBackend` interface with `append()`, `query()`, `count()`. Consumers choose backend at `createTelemetry()` time (Phase 4). | ||
| - **JSONL file format**: Default zero-config backend uses newline-delimited JSON. Append-only, no external dependencies. | ||
| - **`matchesFilter` is shared**: Extracted to `src/storage/matchesFilter.ts` to avoid duplication across backends. | ||
| - **Lazy directory creation**: `FileStorageBackend` creates directories on first `append()`, not at construction time. | ||
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| --- | ||
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| ## Project Patterns | ||
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| Established patterns -- follow these in all packages: | ||
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| - **Module format**: ESM (`"type": "module"` in all packages) | ||
| - **Imports**: Use `.js` extension in relative imports | ||
| - **Types**: Co-locate in `types.ts` per module, export from `index.ts` | ||
| - **Tests**: Place in `tests/` directory at package root, named `*.test.ts` | ||
| - **Quality gates**: `npx nx affected -t build,test,lint` | ||
| - **Shared utilities**: Extract duplicated logic to standalone files named after the export (`filename-match-export` rule) | ||
| - **Empty catch pattern**: Use `flatMap` with `try/catch` returning `[]` for skip-on-error — no logging needed | ||
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| --- | ||
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| ## Known Issues & Gotchas | ||
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| - `count()` in both backends loads all events into memory before counting. Acceptable for Phase 1; optimize in a future phase if needed. | ||
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| --- | ||
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| ## Lessons Learned | ||
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| - The `llm-core/filename-match-export` lint rule requires files with a single export to be named after that export. | ||
| - The comments hook flags all new comments/docstrings — only add when absolutely necessary. | ||
| - `afterEach` must be explicitly imported from vitest (not relied upon as a global). | ||
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| --- | ||
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| ## Next Phase Context | ||
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| ### Target | ||
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| Wave 1: @open-forge/telemetry Phase 2 (Telemetry Core) | ||
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| ### Goal | ||
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| Implement event emission and querying — the `Telemetry` interface: `emit()`, `query()`, `getPipelineSummary()`. | ||
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| ### Critical Context | ||
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| - Storage backends are complete and tested (33 tests passing) | ||
| - Types already defined in `packages/telemetry/src/types.ts` (including `Telemetry`, `PipelineSummary`) | ||
| - Phase 2 deliverable: `src/telemetry.ts` + `tests/telemetry.test.ts` | ||
| - Sequential dependency: 2.1 (`emit`) → 2.2 (`query`) → 2.3 (`getPipelineSummary`) → 2.4 (tests) | ||
| - Requirements covered: F-001, F-002, F-003, F-004, F-005, F-006, F-007, F-013 | ||
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| --- | ||
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| ## Session Resumption Instructions | ||
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| 1. Read this file: cat HANDOFF.md | ||
| 2. Check root status: bash scripts/forge-helper.sh status | ||
| 3. Check package status: bash scripts/forge-helper.sh status --package telemetry | ||
| 4. Resume work on the next phase | ||
| 5. After completion: update this file | ||
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| --- | ||
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| ## Changelog | ||
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| | Date | Wave | Package | Phase | Notes | | ||
| | ---------- | ------ | --------- | ----- | ---------------------------------------- | | ||
| | 2026-04-03 | -- | -- | -- | Created HANDOFF.md | | ||
| | 2026-04-03 | Wave 1 | telemetry | 1 | Storage Layer -- 4/4 tasks | | ||
| | 2026-04-04 | Wave 1 | telemetry | 1 | PR review fixes, matchesFilter extracted | |
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| schema: spec-driven | ||
| created: 2026-04-04 |
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| # telemetry-phase-1 | ||
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| telemetry Phase 1: Storage Layer |
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| ## Context | ||
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| The `@open-forge/telemetry` package currently exports only TypeScript types (Phase 0). The storage layer is the first real implementation — it provides the persistence mechanism that `emit()` and `query()` (Phase 2) will use. The existing `PipelineEvent` and `EventFilter` types in `src/types.ts` define the data model. | ||
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| Constraint: Zero required runtime dependencies for core functionality (per package ROADMAP). | ||
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| ## Goals / Non-Goals | ||
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| **Goals:** | ||
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| - Define a `StorageBackend` interface that decouples telemetry logic from persistence | ||
| - Ship two concrete backends: in-memory (for tests/lightweight) and file-based JSONL (for production default) | ||
| - All backends satisfy the same contract and are interchangeable | ||
| - File backend works zero-config with only a path | ||
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| **Non-Goals:** | ||
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| - SQLite or database backends (deferred per ROADMAP) | ||
| - Concurrent write safety across processes (single-writer assumption for v1) | ||
| - Streaming/pagination for large result sets (can be added later) | ||
| - Hot-swapping backends at runtime | ||
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| ## Decisions | ||
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| ### 1. StorageBackend as a standalone interface (not extending Telemetry) | ||
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| **Decision**: `StorageBackend` is a separate interface with `append()`, `query()`, `count()` — it does NOT extend or overlap with the `Telemetry` interface. | ||
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| **Rationale**: `Telemetry.emit()` will do validation and enrichment before calling `StorageBackend.append()`. Keeping them separate enforces single responsibility. The `Telemetry` implementation (Phase 2) composes a `StorageBackend`. | ||
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| **Alternative considered**: Having `Telemetry` directly implement storage. Rejected — couples business logic to I/O. | ||
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| ### 2. JSONL for file storage format | ||
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| **Decision**: One JSON object per line, append-only. | ||
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| **Rationale**: Simple, human-readable, no corruption from partial writes (each line is independent), streamable, and requires no dependencies. Alternatives like SQLite or binary formats add complexity for marginal gains at this scale. | ||
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| ### 3. File storage creates directories on first write, not on construction | ||
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| **Decision**: The `FileStorageBackend` constructor stores the path. Directory/file creation happens on first `append()`. | ||
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| **Rationale**: Avoids side effects during construction. `query()` on a non-existent file returns empty — no error. | ||
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| ### 4. Query filtering uses in-process filtering | ||
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| **Decision**: Both backends load/scan events and filter in-process using `EventFilter` fields. | ||
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| **Rationale**: Simplicity. At expected telemetry volumes (hundreds to low thousands of events per pipeline), in-process filtering is fast enough. Indexing can be added in a future phase if needed. | ||
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| ## Risks / Trade-offs | ||
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| - **[Large file performance]** → File backend reads the entire file for queries. Mitigation: acceptable for v1 volumes; SQLite backend is in the deferred items list. | ||
| - **[No concurrent writes]** → Single-writer assumption. Mitigation: pipeline is single-threaded; document the limitation. | ||
| - **[JSONL corruption on crash]** → Partial line write possible if process crashes mid-append. Mitigation: each line is independent; partial lines are skipped on read. | ||
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| ## Open Questions | ||
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| None — scope is well-defined by the ROADMAP and requirements doc. |
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| ## Why | ||
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| The telemetry package currently exports only type definitions (Phase 0). Every downstream consumer — the pipeline orchestrator, constraint evaluator, and evaluations integration — needs real storage backends that can persist and query pipeline events. Without a storage layer, telemetry cannot function. This is the critical path: Wave 1 in the unified ROADMAP, blocking all subsequent waves. | ||
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| ## What Changes | ||
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| - New `StorageBackend` interface defining the contract for all storage implementations (`append`, `query`, `count`) | ||
| - In-memory storage backend for testing and lightweight/ephemeral use cases | ||
| - File-based JSONL storage backend as the default zero-config production backend (append-only, no external dependencies) | ||
| - All backends are pluggable — consumers choose at `createTelemetry()` time (Phase 4) | ||
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| ## Capabilities | ||
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| ### New Capabilities | ||
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| - `storage-interface`: Defines the `StorageBackend` contract — `append()`, `query()`, `count()` — that all storage implementations must satisfy | ||
| - `memory-storage`: In-memory `StorageBackend` implementation for testing and lightweight use | ||
| - `file-storage`: JSONL append-only file `StorageBackend` implementation as the default zero-config backend | ||
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| ### Modified Capabilities | ||
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| <!-- No existing capabilities are being modified — this is all new implementation --> | ||
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| ## Impact | ||
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| - **New files**: `src/storage/StorageBackend.ts`, `src/storage/MemoryStorageBackend.ts`, `src/storage/FileStorageBackend.ts`, `src/storage/matchesFilter.ts`, `tests/storage.test.ts` | ||
| - **Modified files**: `src/index.ts` (export storage implementations) | ||
| - **APIs**: New `StorageBackend` interface and two concrete implementations | ||
| - **Dependencies**: Zero runtime dependencies (Node.js `fs` and `path` for file backend only) | ||
| - **Downstream**: Unblocks Phase 2 (Telemetry Core) which needs storage to implement `emit()` and `query()` |
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| ## ADDED Requirements | ||
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| ### Requirement: File storage implements StorageBackend | ||
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| The `FileStorageBackend` class SHALL implement the `StorageBackend` interface, persisting events as JSONL (one JSON object per line) in an append-only file. | ||
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| #### Scenario: Create file storage with path | ||
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| - **WHEN** a `FileStorageBackend` is instantiated with a file path | ||
| - **THEN** it SHALL create the file (and parent directories) if they do not exist | ||
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| ### Requirement: File storage append writes JSONL | ||
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| The `FileStorageBackend.append()` method SHALL serialize the event as JSON and append it as a single line to the storage file. | ||
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| #### Scenario: Append writes one line per event | ||
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| - **WHEN** three events are appended | ||
| - **THEN** the file SHALL contain exactly three lines, each being valid JSON | ||
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| #### Scenario: Append is atomic per event | ||
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| - **WHEN** `append()` is called | ||
| - **THEN** each event SHALL be written as a complete line (no partial writes visible to readers) | ||
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| ### Requirement: File storage query reads and filters JSONL | ||
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| The `FileStorageBackend.query()` method SHALL read the JSONL file, parse each line, and filter by the provided `EventFilter`. | ||
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| #### Scenario: Query filters persisted events | ||
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| - **WHEN** events are appended and then queried with a filter | ||
| - **THEN** only matching events SHALL be returned | ||
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| ### Requirement: File storage persists across instances | ||
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| Events stored by `FileStorageBackend` SHALL be readable by a new instance pointing to the same file. | ||
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| #### Scenario: Data survives instance recreation | ||
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| - **WHEN** events are appended, the instance is discarded, and a new instance is created with the same path | ||
| - **THEN** the new instance SHALL return the previously stored events via `query()` | ||
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| ### Requirement: File storage count avoids full deserialization | ||
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| The `FileStorageBackend.count()` method SHALL count matching events efficiently without requiring all events to be held in memory simultaneously. | ||
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There was a problem hiding this comment. 🧩 Analysis chain🏁 Script executed: #!/bin/bash
# Description: Check FileStorageBackend.count() implementation
# Show the count() method implementation
ast-grep --pattern $'count($$$) {
$$$
}' packages/telemetry/src/storage/FileStorageBackend.ts
# Show if it calls readAll() which loads everything into memory
rg -A 5 'async count\(' packages/telemetry/src/storage/FileStorageBackend.tsRepository: pertrai1/open-forge Length of output: 282 Fix count() to match spec requirement: avoid full deserialization. The spec requires Implement a streaming approach instead—process the file line-by-line, deserializing only to check the filter, without materializing the full event array: async count(filter: EventFilter): Promise<number> {
const content = await readFile(this.filePath, 'utf-8').catch(err => {
if (isNodeError(err) && err.code === 'ENOENT') return '';
throw err;
});
let count = 0;
for (const line of content.split('\n')) {
if (line.trim() === '') continue;
try {
const event = JSON.parse(line) as PipelineEvent;
if (matchesFilter(event, filter)) count++;
} catch {
// Skip malformed lines
}
}
return count;
}For even better memory efficiency with very large files, consider using Node.js streams with 🤖 Prompt for AI Agents |
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| #### Scenario: Count returns correct number | ||
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| - **WHEN** events are appended and `count()` is called with a matching filter | ||
| - **THEN** the correct count SHALL be returned | ||
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| ### Requirement: File storage handles empty or missing file | ||
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| The `FileStorageBackend` SHALL gracefully handle cases where the file does not yet exist or is empty. | ||
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| #### Scenario: Query on non-existent file | ||
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| - **WHEN** `query()` is called before any events are appended (file does not exist) | ||
| - **THEN** an empty array SHALL be returned | ||
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| #### Scenario: Count on empty file | ||
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| - **WHEN** `count()` is called on an empty file | ||
| - **THEN** zero SHALL be returned | ||
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| ## ADDED Requirements | ||
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| ### Requirement: In-memory storage implements StorageBackend | ||
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| The `MemoryStorageBackend` class SHALL implement the `StorageBackend` interface, storing all events in an in-memory array. | ||
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| #### Scenario: Create in-memory storage | ||
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| - **WHEN** a `MemoryStorageBackend` is instantiated | ||
| - **THEN** it SHALL be ready for use with zero configuration | ||
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| ### Requirement: In-memory storage append is synchronous-fast | ||
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| The `MemoryStorageBackend.append()` method SHALL resolve immediately after pushing the event to the internal array. | ||
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| #### Scenario: Append resolves without delay | ||
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| - **WHEN** `append()` is called | ||
| - **THEN** the promise SHALL resolve within 1ms under normal conditions | ||
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| ### Requirement: In-memory storage query filters correctly | ||
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| The `MemoryStorageBackend.query()` method SHALL filter the internal array by all provided `EventFilter` fields. | ||
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| #### Scenario: Query with combined filters | ||
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| - **WHEN** multiple events exist for different pipelines and stages | ||
| - **THEN** `query()` with combined filters SHALL return only matching events | ||
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| ### Requirement: In-memory storage is ephemeral | ||
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| Events stored in `MemoryStorageBackend` SHALL not persist beyond the lifetime of the instance. | ||
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| #### Scenario: Data lost on new instance | ||
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| - **WHEN** a `MemoryStorageBackend` is created, events are appended, and a new instance is created | ||
| - **THEN** the new instance SHALL have zero events |
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Do not continue loop when archive fails.
Line 205’s “warn but continue” risks marking a phase as completed in handoff/status while the change is still unarchived. This can create workflow drift and duplicate future work.
Suggested fix
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🤖 Prompt for AI Agents